Why do people have different skin colors? How are people of different skin colors different? On human adaptation to geoclimatic factors. Why do different peoples have different skin colors? People who have similar skin color

What is leather?

When we think about the human body, we tend to refer to the heart, liver, or brain as “organs.” They have certain functions and they perform them. Did you know that the skin is also an organ of the body?

While other organs take up relatively little space, the skin is spread over the entire body in a thin membrane with an area of ​​20,000 square meters. cm. The number of complex structures present on every centimeter, from sweat glands to nerves, is truly fantastic.

Leather consists of two layers of fabric. One of them is a thicker and deeper layer, the so-called “corium”, and on it is a thin tissue - the “epidermis”. They come together in an amazing way. The lower layer has outgrowths in the form of “papillae”, which penetrate into the upper layer, thus connecting them into a single whole.

Since these “papillae” are located in folds, each area of ​​the skin creates its own pattern. Our fingerprints are actually formed by these folds.

The top layer of skin, the epidermis, does not contain blood vessels. It consists of cells that have already died and become keratinized. We can say that the human body is covered with a horny “shell”. This is very useful as the stratum corneum helps protect us. It is insensitive, so it protects us from pain. Water does not affect it, and it is even a good insulator.

However, the lowest layers of the epidermis are very sensitive. Their job is to create new cells that are produced from the mother cells and, as it were, pushed upward by them. Over time, they stop receiving nutrition and die, turning into a stratum corneum.

Every day, billions of upper keratinized cells fall off during our daily life. But fortunately, just as many new cells are produced every day. Therefore, our skin always remains young.

The skin has 30 layers of keratinized cells. Once the top layer of skin is washed away or worn away, a new one underneath is ready. We will never be able to use all these layers, since a new one always rises from below. In this way, we have the ability to remove stains and dirt from the skin and keep it clean.

People with the whitest skin can be seen in northern Europe and are classified as the Nordic type. The people with the darkest skin live in West Africa. The skin of the inhabitants of Southeast Asia is yellowish. However, most people are not white, black or yellow, but come in hundreds of shades of light, dark or brown.

What is the reason for all these differences in people's skin color? The explanation lies in the chemical processes that occur in the body and skin. Skin tissue contains color components called "chromogens" that are themselves colorless. When certain enzymes act on them, the corresponding skin color appears.

Imagine that a person does not have chromogens or his enzymes do not work correctly on them. Such a person is called an “albino.” This happens to people all over the world. There are albinos in Africa, and they are “whiter” than any white person!

Human skin by itself, without any substance, is milky white. But to this is added a tint of yellow due to the presence of yellow pigment in the skin. Another color component of skin is black, due to the presence of tiny melanin granules. This substance is brown in color, but in large quantities it appears black. Another shade is brought into the skin by the red color of the blood circulating through its tiny vessels. Each person's skin color depends on the ratio in which these four colors - white, yellow, black and red - are combined. All skin colors of the human race can be produced by different combinations of these color components that we all have.

Sunlight has the ability to form melanin, a black pigment, in the skin. Therefore, people living in the tropics have more of this pigment and darker skin. If you spend several days in the sun, the sun's ultraviolet rays also create more melanin in your skin, resulting in a sun tan!

We will continue to educate ourselves =). Since we've discussed skin color, today there's a little scientific and popular information about skin color. Let's remember combinatorics and genetics.
Information used
http://halibi.livejournal.com/231820.html#cutid4

Skin color depends on three elements - melanin (saturation, brown), hemoglobin (reddish tint) and carotene (yellowish tint). Each person has a different combination of these three elements, which results in a unique skin tone. Men have slightly darker skin - hormonal levels also affect it. The skin on different parts of the body is unevenly colored.

The darkness of the skin depends on melanin. Two genes are responsible for the production of melanin, each of which carries two characteristics - dominant and recessive. The dominant characteristic is black skin, the recessive characteristic is white. But this does not mean that one is constantly dominant - they mix. Therefore, 16 combinations are possible.

Let the first gene be labeled with the number 1, and the second with the number 2. The dominant characteristic of black skin color will be M, and the recessive characteristic of white skin color will be m.

Let's decipher the picture

1 - M1M1M2M2 - all dominant characteristics - Black leather

2. MMMm - three dominant and one recessive characteristics - Dark brown skin.

3.MMmm - two dominant and two recessive characteristics - medium brown leather .

4. Mmmm - one dominant and three recessive characteristics - light brown skin color

5. mmmm - all characteristics are recessive - white skin

There are transitional combinations between them.

If you wish, you can calculate how rich the skin your children may have if you are comfortable with combinatorics. Just like that - just for fun.
my type Mmmmm, my husband's type Mmmmm. We can pass on two genes to a child. I got several combinations. Of these, a little MMMm, a little Mmmm, and mostly MMmm. Everything is predictable with us. =) The lightest skin color can be like mine, the darkest can be like my husband’s. And it also happens much more interesting - when the child is darker or lighter than both parents.

Carotene and hemoglobin determine the dominant skin tone (undertone) - either pink (hemoglobin) (top line of the picture) or yellowish (carotene) (bottom line of the picture)

Usually these halftones are taken into account by manufacturers foundations, but this will be a separate topic.

Anthropologists often use the Von Luschan scale to describe skin color. (Von Luschan Chromatic Scale)
To find out your skin color, look at the skin under your forearm, which usually does not tan.

Here is a natural version of the scale

Here's a more convenient digital one

I cannot determine exactly my skin type - either 15 or 16. I can only say that it is clearly beige, i.e. not 14, and clearly not olive, i.e. not 17. 16 seems closer, because the skin is a little yellowish on the hands - but the color may depend on the monitor settings..

Skin saturation is closely related to phototype - skin reaction to ultraviolet radiation. I'll tell you about this next time.

How are people living on our planet different? To answer this question is not so difficult. Of course, by physique, religion, race, gender, worldview, temperament and, most importantly, skin color. It can be white, black, dark, or have a reddish tint.

What is this connected with?

Let's start with the fact that people with a certain skin color could only be found in certain areas of our planet. Redskins - in America, blacks - in the countries of the African continent, whiteskins - in Europe. In this case, we are talking about the territories where their ancestors lived, since in modern world, thanks to the process of migration, people with different skin colors can be found anywhere.

Of course, the place of residence left its mark on the skin color of the people living there. Climate features, solar activity, zonality - all these factors, one way or another, affect the amount of melanin produced by special cells of the human body - melanocytes. But the color of a person’s skin depends on the amount of melanin in the epidermis. The more of this pigment, the darker the skin.

But let's return to the territory of residence and how it affects the production of melanin. Let's give a simple example. The body of a person sunbathing in the sun acquires a dark tint. This happens because under the influence sun rays Melanocytes begin to produce more melanin, which makes the skin darker. This is why people living in hot countries may have black skin. The thing is that they spend a lot of time in the sun, and their epidermis is maximally saturated with melanin. That's the whole secret of black skin.

In white people, melanin is either absent or contained in minimal quantities. Hence, the color of their skin can be white or have a pinkish tint, which is due to the presence of large quantity blood vessels. So, for example, albinos not only have absolutely white skin and hair of the same color, but also a completely colorless iris.

And yet, what role does melanin play in the human body?

As it turns out, its main function is to protect the skin from ultraviolet solar radiation. It is no secret that a person who has received an increased dose of solar radiation runs the risk of developing skin cancer. Melanin, in this case, is a protective filter. It darkens the skin and thereby changes its reflectivity. It turns out that dark skin is less susceptible to ultraviolet rays.

But how did dark-skinned and white-skinned people appear?

Body ancient man was covered with a thick layer of fur that protected it skin from ultraviolet sunlight. In the process of evolution, hair on the human body began to disappear. Why this happened is not known for certain. One way or another, their skin was unprotected from solar radiation.

People living in hot countries were at particular risk. Representatives with dark and dark skin were in a more advantageous position. They were the ones who were able to survive in such extreme conditions. A real natural selection took place, as a result of which the Negroid race appeared.

The exact opposite situation occurred in people with white skin. They lived in cold northern regions, with little ultraviolet radiation. With its deficiency, human bones become fragile, and vitamin deficiency occurs in the body. In such conditions, only people with lighter skin that could absorb more ultraviolet radiation could exist. It was they who supplanted dark-skinned people whose skin blocked ultraviolet rays. For this reason, their offspring suffered from rickets, and the bones could not withstand the load and broke. As a result, only people with light skin, whom we call white-skinned, were able to survive in these places.

We say that people can be black or white, but these two colors by no means exhaust the richness of the color shades of human skin. The color of a person’s skin mainly depends on where on the planet his ancestors lived.

Scientists have experimentally confirmed theories about how people developed different shades of skin color (but so far these are only theories).

What determines skin color?

Skin color depends on a substance called melanin. The more melanin in our skin, the darker it is. When a white-skinned person spends a lot of time in the sun, a lot of melanin is formed in his skin, in other words, he tans. Albinos, who lack melanin in their bodies, have pinkish skin and reddish eyes. This color is due to the translucency of blood vessels through the skin and colorless tissues of the eye. Albinos have completely white hair.

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What is melanin needed for?

The deposition of melanin in the skin is a protective response to ultraviolet radiation from the sun, which can cause skin cancer. As a light shield, melanin absorbs ultraviolet rays and helps protect the skin from damage. The more melanin in the skin, the darker it is and the better protected from ultraviolet radiation. Knowing the importance of melanin in the skin, scientists have developed ideas about how differences in the amount of melanin deposited in the skin appeared among different human races and how these differences developed over millions of years.

Interesting fact: The large amount of melanin in the skin protects it from ultraviolet radiation.

How did people develop different shades of skin color?

Our distant ancestors were covered with a thin layer of wool, which protected their skin from the intense ultraviolet radiation of the hot African sun. Hundreds of thousands of years have passed. As humanity developed, people began to give birth to babies without hair on their bodies. Why? No one knows this. But gradually the light spotted skin of our ancestors turned out to be completely unprotected from the scorching rays of the sun.

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Since dark skin provides better protection from the sun, those individuals that were born darker than their counterparts received an advantage in terms of survival. Since dark skin color was inherited and had the advantages of natural selection, over time the skin color of the inhabitants of Africa became dark. People spread all over the Earth. Those who found their way to the cold north found the climate there was by no means African. In Europe, for example, sunlight is much weaker, especially in winter. This climate also has its disadvantages.

Too much UV rays are harmful, but too little is even worse. Ultraviolet rays are vital for us: under the influence of this radiation, vitamin D is produced in the skin, without which the formation of strong, durable bones is impossible in the body.

Interesting: the earliest humans may have had light, mottled skin similar to that of a chimpanzee underneath its fur.

The dimmer light of the European sun contains much less ultraviolet rays than sunlight in Africa. The first problems probably arose among the dark-skinned aliens, whose skin blocked what little ultraviolet radiation remained in the rays of the northern sun. Some children developed rickets, in which the bones became soft and fragile, they were easily bent and broken.